Katie Ledecky is still queen of the 400m freestyle, but now a younger swimmer is closer to Ledecky than any previous rival.

Ledecky won the 400m free at the Pan Pacific Championships in 3:58.50, the sixth-fastest time ever. She was under world-record pace through 250 meters in Tokyo. None of that is a surprise.

Runner-up Ariarne Titmus has been the recent revelation, clocking an Australian record 3:59.66 on Saturday and finishing about a body length behind Ledecky, outsplitting her in the last half of the race. Nobody has been that close to the American in a major 400m final.

“It’s exciting for me to see how I kind of put the standard out there,” Ledecky said. “I know there a lot of girls that are chasing that. It’s good to see someone get under it [four minutes]. It’s going to push me to go even faster and set the benchmark a little higher.”

Ledecky was not on Saturday’s U.S. 4x100m free relay that took silver behind Australia, which means she has one event left at Pan Pacs, Sunday’s 1500m free.

Ledecky is an overwhelming favorite there, putting her in line to finish the meet with three golds, one silver and one bronze in five events. She captured five golds in six events at 2014 Pan Pacs, breaking two world records.

“It’s been a tough week competing in a different time zone, very far from the U.S., 16-hour time difference,” Ledecky said. “So it’s been a lot harder, I think, than all of us anticipated, knowing that we just got here [Sunday].”

Titmus, 17, became the third woman to break four minutes in the 400m free after Ledecky and former world-record holder Federica Pellegrini.

Titmus ranks third in the world in the 200m free this year but skipped the event at Pan Pacs, where Ledecky finished third behind Canadian Taylor Ruck and Japanese Rikako Ikee. The Tasmanian also ranks third in the 800m free, nearly 10 seconds behind Ledecky, so the 400m may be her sweet spot.

“That’s the goal, to be up there with her and hopefully she’ll enjoy having someone to race,” Titmus said, according to the Sydney Morning Herald. “She hasn’t had anyone to race for a long time, so I’m getting closer. On the sixth lap [from 250 meters to 300 meters] I pulled her back in a bit, but she has a bit more speed than me, and she got away a bit on the seventh 50 and not the last 50. I did the best I could.”

Also Saturday, seven-time 2017 World champion Caeleb Dressel won the 100m butterfly by .57 in 50.75, a quarter of a second off his time from nationals two weeks ago, which remains fastest in the world this year.

Dressel later led off the U.S. men’s 4x100m free relay anchored by Nathan Adrian, edging Brazil by .35. But the Americans were later disqualified for swimming out of order.

Chase Kalisz completed a sweep of the individual medleys, as he did at 2017 Worlds, by taking the 200m IM in 1:55.40, a personal best.

Olympic champion Mack Horton was upset by fellow Aussie Jack McLoughlin in the men’s 400m free — 3:44.20 to 3:44.31. Horton’s 3:43.76 from the Commonwealth Games on April 5 remains fastest in the world this year.

Ikee captured the women’s 100m fly in 56.08, becoming the fourth fastest woman all time. World bronze medalist Kelsi Dahlia of the U.S. was second in 56.44. Olympic and world champion Sarah Sjöström of Sweden, not competing at Pan Pacs, has the 11 fastest times ever.

World silver medalist Yui Ohashi of Japan clocked the fastest women’s 200m IM of the year — 2:08.16.

More: Olympics

SELVA DI VAL GARDENA, Italy (AP) — Skier-snowboarder Ester Ledecka will not be able to follow up her dual sport gold-medal performances at the PyeongChang Olympics with a similar haul of world titles this season.

That’s because the schedule won’t allow it, and she’s not happy about it.

The parallel giant slalom at the world freestyle skiing and snowboard championships in Utah is Feb. 4 — the same day downhill training opens at Alpine skiing worlds in Are, Sweden, and a day before the super-G.

“I was a little bit hoping they would reschedule the snowboard race — put it a week earlier so I could do it both — but they didn’t want to so I have to choose,” Ledecka said Tuesday after placing 29th in a World Cup downhill.

In PyeongChang, Ledecka followed her super-G title by winning the parallel GS in snowboarding — becoming the first athlete to win two golds at one Winter Games using two different types of equipment.

The 23-year-old Czech is the reigning world champion in parallel GS.

Ledecka said she brought up the issue with the International Ski Federation, which governs both sports.

“On one side I see their point. For one athlete why should they do that, right? But from the other side I think I made snowboarding a little more popular, and I think a lot of fans would be happy to see me compete in both,” Ledecka said. “It’s their decision, and I have to respect it.”

Ledecka has not decided which worlds she’ll compete in. She’s currently going back and forth between the snowboard and ski circuits.

Last week, she finished first and second in two parallel GS events in Italy and then switched to downhill skis this week. She was fastest in a downhill training run Monday before finishing 29th in Tuesday’s race.

“I think I can decide right before,” Ledecka said. “But it will probably be early, so I’m well prepared.”

Viletta, who did not defend his Olympic title in PyeongChang, has not raced on the World Cup since tearing a knee ligament in a December 2016 super-G crash. He hasn’t raced anywhere since another knee ligament tear in a lower-level race in March.

Viletta took gold in Sochi despite having one World Cup podium to his name (from more than two years earlier). Viletta was 14th in the downhill part of the Olympic combined, then had the second-fastest slalom to win by. 34 over Croatian Ivica Kostelic.

“I did not think this was possible; I did not expect to win, even after I had the lead today,” Viletta told reporters after the race. “But on one day, I had the perfect day.”

Viletta was the lowest-ranked racer in the downhill to come back to win the Olympic combined since the format changed from two slalom runs to one in 2010. He is Switzerland’s lone Olympic men’s Alpine champion from the last two Winter Games.

The combined’s place at the Olympics and world championships and on the World Cup is in peril as the International Ski Federation has incorporated more parallel slalom and giant slalom races in recent years.